The invention concerns a front bulkhead for a motor vehicle, the bodyshell floor of which is fitted with a tunnel. More particularly, the invention concerns a front bulkhead for a vehicle with the engine mounted at the rear.
The bulkhead is a generally flat partition of vertical and transverse orientation, which is intended to ensure comfort and maximum safety for the vehicle passengers. Reference is made to documents FR 2803813, EP 1073579 and EP 1920999 which illustrate examples of a front bulkhead for a motor vehicle.
Amongst others, the bulkhead ensures the acoustic isolation of the cab. Damping elements such as foams are for example glued onto the bulkhead to absorb a large portion of the vibrations and thus reduce the sound level and vibrations in the cab.
An important function of the bulkhead is to ensure the safety of the vehicle passengers, in particular on a frontal impact. The front bulkhead is therefore generally designed so as to prevent any direct contact between the front part of the vehicle and the cab.
Another function of the front bulkhead is to allow the passage of elements which extend both into the cab and into the front part of the vehicle, such as the steering column, the control pedals for the engine and brakes of the vehicle.
Other elements extend in the longitudinal plane of the vehicle and must therefore generally pass through the cab and the front bulkhead. This is the case for example for the vehicle engine's exhaust pipe. The bodyshell floors of motor vehicles are generally equipped with a tunnel extending in the longitudinal direction of the vehicle, the function of which is to protect these elements and in particular the engine exhaust pipe.
Also, the front wheels of some vehicles are not always fully situated in front of the front bulkhead.
Thus it appears in documents FR 2803813, EP 1073579 and EP 1920999 that these front bulkheads are provided with:                openings for the cables of the acceleration, clutch and brake pedals and for the steering column,        recesses for the front wheels of the vehicle, and        a cutout for the tunnel of the bodyshell floor.        
A front bulkhead is generally produced by deep-drawing. A rectangular metal sheet is deep-drawn to produce the openings, recesses and cutout. Deep-drawing also allows adaptation of the bulkhead shape to the architecture of the motor vehicle. The rectangular metal sheet is naturally of a greater mass than the finished part. Part of the sheet constitutes the finished part while the remainder constitutes waste, i.e. unused material.
In production of a bulkhead, the material usage represents the ratio between the mass of the finished part and the mass of the sheet used. During production, the aim is to lose as little material as possible when manufacturing the part. Therefore, generally, the aim is to maximize the material usage. The material usages generally achieved are of the order of 55%.